If you previously had bought from the AppStore with your paypal ID:
create a new "blackberryID" with some valid email adress like:
and, then link your paypal account to it.
Afterwards, your previously downloaded apps are again availible.

However: if you agree to link your paypal account, it will automatically add some auto-billing feature, with a limit of $1200.
If you dont like this, login to your paypal account, go into your profile, and cancel the "preapproved payments plan".